1. Field of the Invention
The present invention relates to wood burning fireplaces. More particularly, the present invention relates to a novel stand off and improved top and exhaust structure for gas and wood burning fireplaces.
2. Description of the Prior Art
Heretofore exhaust stacks on stoves, fireplaces and gas water heaters have been known to overheat and create a hazardous condition that could result in igniting flammable walls and roof structures.
A common cure for a hot stack on a gas water heater is a well known vent collar which mixes room air with the exhaust gas to lower the stack temperature. Domestic boilers and furnaces have adapted the same principal as a vent collar by directing hot exhaust gases through a hood or plenum which pulls room air into a box shaped chamber and mixes it with room air. The cooled mixture is then directed into a conventional exhaust stack. The problem with vent collars and vent hoods is that they often require a large number of individual pieces that add to the stack cost.
Another remedy for a hot exhaust stack for fireplaces is to provide a coaxial or two piece exhaust stack which is mounted on and supported by the fireplace. As will be explained in greater detail hereinafter, the room air is pulled into the space between the larger diameter pipe and the smaller exhaust pipe to insulate or isolate the inner pipe which contains the hot exhaust gas. The outer pipe with an air space between it and the exhaust pipe forms an effective insulator. Prior art coaxial pipe stacks are known to be expensive and can be complex.
It would be desirable to provide in a wood or gas fireplace, an improved lightweight and low cost cooled exhaust stack and top support structure which would permit it to be directly coupled to a conventional coaxial exhaust stack without expensive insulating structures or vent collars.